Those are manufactured things, not evolved beings. It sounds a little specious to say that evolution looks for efficiency but then organisms somehow evolve from presumably single celled organisms to multi-celled organisms with hundreds or thousands of hugely complex internal systems working together to make the organism go. I cant even comprehend how that’s remotely more efficient.
How about the jellyfish? It’s highly complex in its feeding mechanism, and highly efficient in motion. Yet it’s method of propulsion is incredibly simple, not complex at all.
Complexity is not required by evolution! A monkey’s tail is considerably more complex than that of the gorilla or human (we both have essentially none - just a few remnant bones), and it serves the needs of the monkey quite well - an animal that is very light.
Likewise a bird’s skeleton. Considerably less dense and complex than a human’s, but that is what allows it to fly.